Maybe some people worked a lot on their toons, dont have time for a new toon again and would like to benefit from what they achieved so far?
And there is quite a few 150 twinks who do rather well so far in pvp AND s10, and against 174 there still is some chance for a fun fight, while at 150 vs 200 there isnt.
I love my 150 toons and i like them on bs as well as s10, but against lvl 200 toons, that fun is over .
And yes i also enjoy my lvl 170 agent.